How to Sort a String Array Alphabetically While Prioritizing Numerical Values?

Maintaining Alphabetical Order while Prioritizing Numeric Values in String Arrays

Sorting strings alphabetically is a standard task, but how do you handle scenarios where strings also represent numbers while maintaining the numerical order? Here's a solution that addresses this challenge.

Consider the following code:

string[] things= new string[] { "105", "101", "102", "103", "90" };

foreach (var thing in things.OrderBy(x => x))
{
    Console.WriteLine(thing);
}

This code attempts to sort an array of numeric strings alphabetically, but the output is not as desired:

101, 102, 103, 105, 90

To achieve the expected output:

90, 101, 102, 103, 105

you need to pass a custom comparer into OrderBy. Enumerable.OrderBy allows you to specify a custom comparer for sorting.

Here's an implementation using a SemiNumericComparer:

string[] things = new string[] { "paul", "bob", "lauren", "007", "90" };

foreach (var thing in things.OrderBy(x => x, new SemiNumericComparer()))
{    
    Console.WriteLine(thing);
}

The SemiNumericComparer class defines a method to determine whether a string is numeric and provides a comparison method:

public class SemiNumericComparer: IComparer<string>
{
    /// <summary>
    /// Method to determine if a string is a number
    /// </summary>
    /// <param name="value">String to test</param>
    /// <returns>True if numeric</returns>
    public static bool IsNumeric(string value)
    {
        return int.TryParse(value, out _);
    }

    /// <inheritdoc />
    public int Compare(string s1, string s2)
    {
        const int S1GreaterThanS2 = 1;
        const int S2GreaterThanS1 = -1;

        var IsNumeric1 = IsNumeric(s1);
        var IsNumeric2 = IsNumeric(s2);

        if (IsNumeric1 &amp;&amp; IsNumeric2)
        {
            var i1 = Convert.ToInt32(s1);
            var i2 = Convert.ToInt32(s2);

            if (i1 > i2)
            {
                return S1GreaterThanS2;
            }

            if (i1 < i2)
            {
                return S2GreaterThanS1;
            }

            return 0;
        }

        if (IsNumeric1)
        {
            return S2GreaterThanS1;
        }

        if (IsNumeric2)
        {
            return S1GreaterThanS2;
        }

        return string.Compare(s1, s2, true, CultureInfo.InvariantCulture);
    }
}

When applied to the array of strings, the SemiNumericComparer sorts the strings first by alphabetical order and then by numerical value, providing the desired output.

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